1. Field of the Invention
The present invention relates to a system that uses a plurality of microjets located on a leading edge of a cavity located on an aircraft, which microjets issue a jet flow toward the trailing edge in order to reduce the unsteady air flow over whenever the cavity is exposed.
2. Background of the Invention
Aircraft in flight desire a relatively smooth and steady air flow over substantially the entire body of the aircraft. Such smooth and steady air flow reduces drag, air turbulence and pressure loading on various areas of the aircraft, resulting in increased performance including higher speed, greater stability, and handling, and reduced pressure and acoustic loading on the aircraft. Aircraft design including materials selection been made great strides in achieving this relatively smooth and steady air flow over most of the aircraft in order to produce aircraft that have superior performance characteristics.
One area or groups of areas of an aircraft that continue to have highly unsteady air flow over such areas are the cavities of an aircraft. Such cavities include landing gear wheel wells and internal weapons bays. These cavities tend to be closed or otherwise covered during flight and in such covered orientation, the cavities have relatively steady air flow thereover. However, at times, such coverings must be removed and the cavities exposed. This can occur when the aircraft is taking off and landing and during weapons systems release. When these cavities are exposed, a highly unsteady air flow passes over the cavities resulting in high dynamic pressures and acoustic loads in cavities and within the vicinity of the cavities. Such loading results in decreased and less stable flight dynamics of the aircraft as well as increased noise within the aircraft. Additionally, the unsteady air flow acts on the stores released from the cavities resulting in decreased delivery accuracy in the case of a weapons payload. Furthermore, the high dynamic loads in and around the cavity results, over time, in structural fatigue at the areas of the high loads.
In order to increase the stability of air flow over aircraft cavities, and thus reduce the high pressure loading, various methods have been proposed. Such methods fall into one of two broad categories. The first type of air flow control systems are passive in nature, such as fixed deflectors. The performance of such passive systems is marginal and such passive systems lack uniform response over a desired operating range. The other major type of air flow control systems for cavities are dynamic in nature. While such dynamic systems tend to have superior performance characteristics over passive systems, these types of systems either require too much power to effectively operate and thereby reduce available power to the aircraft's main functions, or tend to adversely affect aircraft performance whenever the systems are not needed, such as when the cavities are not exposed.